As known, bimetallic pipes are made up of two pipes of different material attached to each other telescopically by means of particular methods of manufacture which, though deferring in the process, are all intended to attain a product similar to a single pipe as the final result.
The fields of use of bimetallic pipes vary widely and, in particular, there are numerous sectors in which operations leading to high outer stresses alongside a high risk of corrosion of the pipes due to direct contact with corrosive and potentially hazardous fluids such as the ones used, for example, in the chemical, petrochemical, fertilisers, thermal power stations and nuclear plants, etc., are performed.
Consequently, the pipe to be attached must have complementary characteristics given that the outer one, preferably made of steel or its alloys, must resist against particularly heavy loads while the inner one, preferably made of copper, aluminium, titanium, zirconium or their alloys, etc., must allow contact with corrosive fluids and/or fluids under high operation pressure.
In order to obtain a perfect attaching of the two pipes inserted one into the other it is indispensable that the coupling process used, alongside avoiding the formation of oxygen or the like between the contact surfaces, there be guaranteed resistance against detachment by traction as well as duration of the coupling over time.